A car weighing 500 kg moving against a resistance of 500 N, accelerates from rest to `20 m//s` in 100m `(g = 10m//s^2).` The work done by the engine of the car is :

Options

A. `1.0 xx 10^J`
B. `1.5xx10^5J`
C. `1.05 xx 10^5 J`
D. the information given is insufficient

Answer

B

Explanation

(b) `As upsilon^2 - u^2 = 2as, a = (upsilon^2 - u^2)/(2s) = ((20)^2 - 0)/(2xx100) = 2 m//s^2`
As `f_1 = 500 xx 2 =1000 n and f_2` (force of friction) = 500 N, total force exerted by the engine,
`F = f_1 + f_2 = 1500 N`
Work done, `W= F s = 1500 N xx 100m =150000 j = 1.5 xx 10^5 J`